Design of Flexible and Rigid Pavements

Dr Ong Ghim Ping Raymond

Department of Civil Engineering

National University of Singapore

IES Preparatory Course PE Exams Course 2010CE 204 Transportation

Foster and Ahlvin Influence Chart for Vertical Stresses

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100%z

p

z

a

Foster and Ahlvin Influence Chart for Vertical Deflections

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Problem: Compute the ESAL of this truck on a flexible pavement with SN=4 and terminal PSI pt = 2.5.

Solution:

ESAL load = 0.10 + 0.89 + 0.89

= 1.88 ESAL per truck

Types of Axle Loads

• Single axle load: wheels with distance more than 1 m apart

• Tandem axle load: two or more consecutive axles between 1 m to 2.44 m spacing

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10 kips 32 kips 32 kips

Flexible Pavements

Problem: Compute the ESAL of this truck on a rigid pavement with D=9 in. and terminal PSI pt = 2.5.

Solution:

ESAL load = 0.08 + 1.49 + 1.49

= 3.06 ESAL per truck

Types of Axle Loads

• Single axle load: wheels with distance more than 1 m apart

• Tandem axle load: two or more consecutive axles between 1 m to 2.44 m spacing

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10 kips 32 kips 32 kips

Rigid Pavements

UK Road Note 29Step 3: Determining Thickness of Sub-base Layer

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UK Road Note 29 Step 4: Rolled Asphalt Roadbase: Minimum Thickness of Surfacing and Roadbase

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UK Road Note 29 Dense Macadam Roadbase: Minimum Thickness of Surfacing and Roadbase

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UK Road Note 29 Lean Concrete, Soil-Cement and Cement-Bounded Granular Roadbase: Minimum Thickness of Surfacing

& Roadbase

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UK Road Note 29 Wet-Mix and Dry-Bound Macadam Roadbase: Minimum Thickness of Surfacing and Roadbase

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AAHSTO Flexible Pavement Nomograph

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UK Road Note 29: Thickness of Reinforced and Unreinforced Concrete Slabs

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UK Road Note 29: Weight of Reinforcement Fabric and Area of Steel per Unit Width of Pavement

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UK Road Note 29: Joint Spacing for Jointed Reinforced Concrete Pavement

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Estimating k assuming semi-infinite subgrade depth

16Correction of k to account for presence of rigid foundation near surface

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Estimating Relative Damage u using slab thickness and composite k value

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Correction of k Value due to Loss of Support

AASHTO Rigid Pavement Nomograph I

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H. Determine Slab ThicknessUse nomograph (p. 68-69) to determine required slab thickness

AAHSTO Rigid Pavement

Nomograph - II

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